(1) Field of the Invention
The present invention relates to the field of collision avoidance systems for aircraft that generate warnings relating to obstacles that are to be avoided and that communicate those warnings in flight to a pilot of an aircraft.
The present invention relates more particularly to collision avoidance apparatus for an aircraft making use of various collision avoidance systems and also to a system for managing the warnings generated individually by the various collision avoidance systems. Such a warning management system generates a consolidated warning relating to the presence in the close environment of the aircraft of obstacles that have previously been detected by the various collision avoidance systems, and it communicates those warnings to the pilot of an aircraft, in particular by means of a visible display and/or by audible means.
(2) Description of Related Art
In the field of aviation, aircraft are fitted with collision avoidance apparatus for generating collision avoidance warnings relating to obstacles that are to be avoided and that have been detected in the close environment of the aircraft, and for displaying those warnings in flight to the pilot. Conventionally, such collision avoidance apparatus combines various collision avoidance systems associated with respective specific ways of detecting obstacles, and it includes means for communicating said collision avoidance warnings.
The various collision avoidance systems may be classified in particular depending on the obstacles that they detect, and also on the urgency and on the kinds of action the pilot needs to take on how to guide the aircraft in order to avoid the detected obstacles. One or more collision avoidance warnings indicating the presence of one or more obstacles to be avoided are communicated to the pilot by display means and/or by audible means, depending on the classification of collision avoidance systems and on the urgency of the action to be taken by the pilot in order to avoid the obstacle(s).
Conventionally, collision avoidance apparatus on board an aircraft may potentially comprise a plurality of collision avoidance systems including at least the following collision avoidance systems:
a “terrain” collision avoidance system, such as for example a helicopter terrain awareness and warning system (HTAWS);
a “perimeter” collision avoidance system, such as for example an obstacle warning system (OWS);
an “aircraft” collision avoidance system such as for example an airborne collision avoidance system (ACAS) or a traffic collision avoidance system (TCAS); and
a “flight management” collision avoidance system that makes use of the resources of a flight management system on board a rotorcraft, such as for example a flight management system (FMS).
A terrain collision avoidance system is dedicated to informing the pilot about a danger of the aircraft colliding with potential obstacles that are identified and listed in a terrain database. One or more collision avoidance warnings, referred to as “terrain” warnings, are communicated to the pilot by audible means and/or by display means in the event of there being a danger of collision between the aircraft and the obstacles, with a predefined duration being taken into account. Such terrain warnings may be communicated to the pilot in particular as follows:
by visual information on a color scale, typically such as a scale of colors varying progressively towards hot colors (from green and/or amber towards red, in particular), depending on the urgency with which the pilot needs to take action in order to avoid the obstacle(s) detected by the terrain collision avoidance system; and
map information locating the site of a potential collision between the aircraft and an obstacle, said map information commonly being accompanied by an indication of ground height at the collision site.
A perimeter collision avoidance system conventionally makes use of telemeter sensors commonly fitted to aircraft for detecting the presence of obstacles, if any, on the trajectory of the aircraft. The perimeter collision avoidance system is dedicated to telemeter detection in real time of the presence of obstacles, if any, in a given flight perimeter directed at least towards the front, and possibly also around the aircraft. Such obstacles include in particular obstacles on the ground and possibly also obstacles in the air, e.g. aircraft or localized weather phenomena.
The perimeter collision avoidance system generates one or more collision avoidance warnings, referred to as perimeter warnings. Perimeter warnings are communicated to the pilot by display means and by audible means, while taking account of a predetermined duration between the potential collision between the aircraft and an obstacle detected in the environment close to the trajectory being followed by the aircraft.
Perimeter warnings are displayed in particular in the form of on/off visual information in color (in particular a hot color such as red) that is displayed at a predefined threshold duration prior to collision. Perimeter warnings may also be displayed using a color scale, that varies, as mentioned above, depending on the urgency with which the pilot must take action in order to avoid the obstacle(s) detected by the perimeter collision avoidance system. Perimeter warnings are also potentially associated with visual information relating to the bearing position of the obstacle relative to the trajectory being followed by the aircraft.
An aircraft collision avoidance system supplies the pilot with one or more aircraft collision avoidance warnings relating to the movements of another aircraft nearby. Aircraft warnings are generated by the aircraft collision avoidance system on the basis of data that is exchanged between aircraft flying close to each other.
In the event of a potential collision between two aircraft, an aircraft collision warning is commonly communicated to the pilot in the form of visual information giving the position of the other aircraft. If the danger of collision persists, the visual information is accompanied by an audible message and a piloting instruction is communicated to the pilot in order to avoid a collision between the aircraft. Such a piloting instruction may potentially be an avoidance maneuver to be performed vertically upwards, vertically downwards, or less often to maintain the current trajectory of the aircraft, and it may also indicate monitoring to be performed by the pilot concerning the vertical speed of the aircraft.
A flight management collision avoidance system makes use of a flight plan previously determined by means of a flight management system on board the aircraft. The flight management collision avoidance system identifies a potential collision between an obstacle on the ground and the aircraft flying in compliance with the flight plan. The flight management collision avoidance system generates one or more collision avoidance warnings, referred to as flight-plan obstacle warnings that may be presented in the same form as terrain warnings.
The various collision avoidance systems described above are those that are most commonly used, however collision avoidance apparatus on board an aircraft may include other collision avoidance systems dedicated to detecting specific obstacles and/or to using particular ways of generating collision avoidance warnings and communicating them to the pilot.
For example, there are weather collision avoidance systems such as the weather X radar (WXR) collision avoidance systems, dedicated to detecting localized weather phenomena in the vicinity of the aircraft and displaying them.
In this context, it commonly happens that a plurality of collision avoidance warnings generated by one or more collision avoidance systems are communicated simultaneously to the pilot. However such a multiplicity of simultaneous collision avoidance warnings may potentially be the source of computation conflicts in terms of communicating them in good time, and is also a source of difficulty for the pilot who must respond quickly, generally in less than one minute, in order to avoid a collision between the aircraft and the various obstacles associated with the collision avoidance warnings that are being communicated.
Such pilot response difficulties are particularly relevant when the aircraft is a rotorcraft. A rotorcraft is an aircraft that is likely to be flying close to the ground, possibly at high speed, and/or that may be flying at low speed or that may be hovering. Such flight conditions make it necessary for the pilot to respond even more quickly in the event of a plurality of collision avoidance warnings being communicated simultaneously relating to nearby obstacles that might be numerous and varied.
Nevertheless, the collision avoidance warnings that are individually communicated by the various collision avoidance systems are useful and possibly even necessary. It is difficult to envisage reducing and/or simplifying the amount of information in the individual warnings being communicated to the pilot by each of the collision avoidance systems. That is why man/machine interfaces have been developed that enable a consolidated warning to be communicated to the pilot in addition to communicating the collision avoidance warnings generated individually by the various collision avoidance systems.
For example, man/machine interfaces have been proposed that generate and communicate a consolidated warning relating to one particular collision avoidance warning that is deduced as having the highest priority from among a plurality of collision avoidance warnings that are generated individually by various collision avoidance systems. Which collision avoidance warning has the highest priority is deduced by applying predefined selection criteria, e.g. relating to the attitude and the position of the aircraft relative to the various obstacles detected by the various collision avoidance systems.
On this topic, reference may be made to Document EP 0 987 562 (Allied Signal Inc.), which discloses such a man/machine interface that generates a warning that is consolidated on the basis of priorities between various previously-generated collision avoidance warnings.
By way of example, proposals have also been made for man/machine interfaces that generate a consolidated warning relating to detecting a group of obstacles and communicating it to the pilot. Such a group of obstacles is previously identified by applying predefined criteria, such as proximity. Such provisions are implemented in particular by a terrain collision avoidance system.
On this topic, reference may also be made to Document EP 1 946 284 (Thales SA), which discloses such a man/machine interface for generating a consolidated warning relating to detecting a group of obstacles.
With reference to FIG. 1 of the accompanying sheet of drawings, man/machine interfaces have also been proposed for rotorcraft, which generate a consolidated warning relating to various collision avoidance warnings as generated individually by a plurality of collision avoidance systems, and which communicate the consolidated warning to the pilot. The consolidated warning is communicated to the pilot by a display in the form of a table, making use of all or some of the data specific to various collision avoidance warnings generated individually by the various collision avoidance systems.
A plurality of columns are allocated respectively to the various collision avoidance systems, e.g. as in the example shown to a TCAS aircraft collision avoidance system, an HTAWS terrain collision avoidance system, an OWS perimeter collision avoidance system, and an FMS flight management collision avoidance system. Each column displays one or more rows of colors, with colors potentially varying depending on the urgency of the action that the pilot needs to take in order to avoid the obstacles, in application of a color scale that varies from an amber color to a red color, as described above.
It can be seen that research continues for integrated man/machine interfaces that generate a consolidated warning for use with collision avoidance apparatus implementing a variety of collision avoidance systems in order to provide the pilot of the aircraft with a tool for providing assistance in decision taking that gives the pilot a rapidly understandable overview of a potential emergency situation.
This research is based in particular on determining selection criteria for producing a consolidated warning that is found to be pertinent, and on determining which data to extract from the various collision avoidance warnings in order to generate the consolidated warning. Such research is also based in particular on how to communicate the consolidated warning to the pilot of the rotorcraft in ways that are ergonomically appropriate. Beyond discovering the preferences of aircraft pilots, communicating the consolidated warning in an ergonomically appropriate manner is crucial for informing the pilot quickly and effectively about the state of the aircraft relative to the outside environment and for making the pilot's task easier in terms of the obstacle avoidance maneuvers that need to be performed. The effectiveness of the man/machine interface and the behavior of the aircraft while avoiding obstacles are thus improved.
On this topic, reference may be made for example to Document U.S. Pat. No. 6,700,482 (Honeywell Int. Inc.), which proposes making use of multichannel sound communication to communicate a consolidated warning and/or an emergency collision avoidance warning to the pilot of an aircraft.
For greater understanding of the technological environment of the present invention, reference may also be made to the following documents: EP 2 506 105 (Honeywell Int. Inc.); FR 2 913 800 (Thales SA.); US 2007/182589 (My Tran); US 2004/239529 (My Tran); EP 2 237 126 (Eurocopter France); and EP 2 450 868 (Rockwell Collins France).